Buggy code:
public class Helper { public static void copy ( PrintWriter out , InputStream stream ) throws IOException { } public static < K , V extends Comparable < ? super V > > Map < K , V > sortByValueDescending ( Map < K , V > map ) { } public static void showMap ( Map < String , Map < String , Double > > map ) { } public static void showMap ( Map < String , Map < String , Double > > map , int innercap ) { } public static void showMap ( Map < String , Map < String , Double > > map , int outercap , int innercap ) { } public static void showItems ( List < RecommendedItem > itemlist ) { } public static Map < String , Map < String , Double > > swapMap ( Map < String , Map < String , Double > > map ) { } public static < K > void incrementMapValue ( Map < K , Integer > map , K key ) { } public static < K > void incrementMapValue ( Map < K , Integer > map , K key , Integer value ) { } public static < K > void incrementMapValue ( Map < K , Double > map , K key , Double value ) { } public static < K > Integer sum ( Map < K , Integer > map ) { } public static Double computeCosSimilarity ( List < Integer > v1 , List < Integer > v2 ) { } public static Double computePearsonSimilarity ( List < Integer > v1 , List < Integer > v2 ) { } public static Double computeAdjustedCosineSimilarity ( List < Integer > v1 , List < Integer > v2 ) { } public static Double computeAdjustedCosineSimilarityDoubles ( List < Double > v1 , List < Double > v2 ) { } public static Double computeAdjustedCosineSimilarity ( List < Integer > v1 , List < Integer > v2 , Double v1mean , Double v2mean ) { } public static Double computeAdjustedCosineSimilarityDoubles ( List < Double > v1 , List < Double > v2 , Double v1mean , Double v2mean ) { } public static Double computeAdjustedCosineSimilarity ( List < Double > v1 , List < Double > v2 , boolean adjusted ) { } public static Integer getOverlapping ( List < Integer > v1 , List < Integer > v2 ) { } public static < T > T [ ] applyPaging ( T [ ] array , Map < String , String > param ) { } public static < T > List < T > applySubList ( List < T > items , Map < String , String > param , int topN ) { } public static < T > List < T > applySubList ( List < T > items , int topN ) { } public static boolean isIntegerRegex ( String str ) { } public static File createOrGetDir ( String path ) { } public static Map < String , String > splitIdKeyConfig ( String config ) { HashMap < String , String > result = new HashMap < > ( ) ; String [ ] split = config . split ( "," ) ; for ( String s : split ) { if ( ( s != null ) && ( ! ( s . isEmpty ( ) ) ) ) { if ( s . contains ( "@" ) ) { String [ ] idSplit = s . split ( "@" ) ; if ( ( idSplit . length ) > 1 ) { <START_BUG> result . put ( idSplit [ 0 ] , idSplit [ 1 ] ) ; <END_BUG> } } else { result . put ( s , s ) ; } } } return result ; } public static class Keys { public static final String ExperimentId = "experiment-id" . intern ( ) ; public static final String OutputParam = "output" . intern ( ) ; public static final String ItemId = "item-id" . intern ( ) ; public static final String UserId = "user-id" . intern ( ) ; public static final String RelationId = "relation-id" . intern ( ) ; public static final String FromId = "from-id" . intern ( ) ; public static final String ToId = "to-id" . intern ( ) ; public static final String SourceId = "source-id" . intern ( ) ; public static final String DataBuilderId = "data-builder-id" . intern ( ) ; public static final String RecommenderId = "rec-id" . intern ( ) ; public static final String Type = "type" . intern ( ) ; public static final String DataSplitterId = "splitter-id" . intern ( ) ; public static final String State = "state" . intern ( ) ; public static final String Dir = "dir" . intern ( ) ; public static final String ID = "id" . intern ( ) ; public static final String TopN = "topN" . intern ( ) ; public static final String MetricIDs = "metric-ids" . intern ( ) ; public static final String Value = "value" . intern ( ) ; public static final String RecommenderBuilderId = "rec-builder-id" . intern ( ) ; public static final String RecommenderBuilderIdPrefix = "rec-builder-" . intern ( ) ; public static final String Page = "page" . intern ( ) ; public static final String PageSizeKey = "page-size" . intern ( ) ; public static final String Count = "count" . intern ( ) ; public static final String Key = "key" . intern ( ) ; public static final String TimeStamp = "timeStamp" . intern ( ) ; public static final String SplitType = "split-type" . intern ( ) ; public static final Integer PageSize = 10 ; public static final String Percentage = "percentage" ;

Fix:
result . put ( idSplit [ 1 ] , idSplit [ 0 ] ) ;